1. Field of the Invention
This invention relates to depth-adjusting systems for tools, particularly to depth-adjusting systems for power driven screwdrivers, in which a subassembly including two molded plastic parts is connected to the nose portion of the screwdriver with a snap-action, permitting quick replacement of a screwdriver bit without disturbing the depth setting.
2. Description of the Prior Art
Previous depth-adjusting systems have included complicated, spring-biased mechanisms which have required several machined parts, as well as a certain degree of care by the operator to avoid losing the parts during disconnection of the system.
Another prior art system includes a two-piece plastic subassembly. One piece is a collar which is rotatably connected to the housing of a power tool and includes an internal thread. The other is a small-diameter depth locator member rotatably connected to the collar using the same thread as is used to connect the collar to the housing. Ridges on the locator member engage longitudinal ribs formed on the interior of the collar to maintain a particular depth setting. While this prior art depth locating system does permit an operator to replace the bit without having to change the depth setting on the depth locator, the operator must nevertheless assemble the depth locator to the housing of the tool by rotating the collar through several turns, thereby taking an additional increment of time. Furthermore, because the operator must change the depth setting by rotating the depth locator member relative to the fixed, large-diameter collar, very little mechanical advantage is available to the operator, who must use significant force to overcome the interaction of the ridges on the locator with the respective longitudinal ribs formed on the collar.